Hydronic system as base load, forced air as peak load...

I have a new house being built, and of course am running into brick walls with the HVAC contractor. He is more accustomed to commercial and industrial buildings where all the thinking and engineering has been done for him, so all he has to do is install. What I want is hydronic heat, under the floor, stapled up between floor joists (over an unfinished basement that also has foam insulation on the outside of the exterior walls). I plan on using foam board with foil on one side, cut to fit loosely enough to be easily installed and/or removed from the engineered joists. That will be the base load, but as we all know, changing the temperature of a hydronic system takes hours. So, since we have to pre-wire, pre-plumb, etc. for a forced air system anyway for air conditioning (not my idea, but making sure that the house can be sold someday without major mods), I want a hot water coil in the air handler to boost the air temperature in those occasional events when the domestic supervisor is cold and wants heat right NOW. She tends to run thermostats either all the way up or down, thinking she will reach her comfort zone faster that way. Really irritating in the car, I can tell you! That is the heating side of it, from my viewpoint. He says a simple gas furnace is the way to go, because that is pretty much what he does in houses. A compromise would be a modern gas furnace with 2 levels of heating, and 2 fan speeds that won't have to run very often based on the hydronic doing most of the work. HVAC guy also wants me to put in 4 to 5 tons of AC for a house in Logan, Utah. I only have 4 tons for our house in Phoenix, Arizona, and it gets a bit hot there. The Utah house is smaller by 150 sq. ft. but also has a 900 sq. ft. loft and bonus room area upstairs that is pretty much open to the main floor. We won't be going up there much, though. I warned him about oversizing, letting him know that I could live with a system that runs too often or too long than one that short cycles. I can always add to the hydronic if I have to. I won't put in the outside portion of the AC for at least the first year, thinking that I have designed the house well enough to need very little cooling assistance, and if it does, I prefer either a whole house fan, or evaporative cooling. Does this sound like sound, and sane, thinking on my part?
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If you're going with a low mass radiant system, it's a whole different critter from what you or your significant other are accustomed to. Use transfer plates under the sub floor. Limit the carpeting to throw rugs or small area rugs. It will be very comfortable as is assuming the design and installation are correct.
Don't use a setback with the radiant system.
Make sure you go with a modulating condensing boiler.

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Entry, dining, kitchen are all tile. Those rooms will get a lot of sun as well. Gonna try to use wood floors and area rugs every where else, may have to fight the wife on that idea for the bedrooms, hence the forced air system becomes even more necessary to back up the hydronics. I was thinking of getting thicker grade aluminum foil to use as transfer plates, just add some spray glue and put that up first.

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Don't cheap out on the transfer plates. You spending a good buck for a premium system. If you need to save the money you'd spend on transfer plates go to panel radiators with an outdoor reset control and constant circulation. Somewhat less money. A high amount of radiate. Room by room control. You give up a little wall space but these come in a huge variety of sizes.
We're just finishing up a system like this and the clients are extremely happy with it.
Or go with radiant floor in the tile/wood areas and higher temp panel rads in the BRs. We've done this as well. Although you may want to have separate control over the areas with high solar gain vs the areas with low solar gain.

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Wife has already vetoed radiators of any kind, but I am working on it....With the basement open and unfinished, I have the flexibility to add parts and pieces as needed. There are places to hide radiators, like where the bed meets the wall, she will never see that. And behind a couch in the living room.
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If you're going to hide them you don't want panel rads, you want baseboard (ugh). Too much of the panel rads heating is via radiant.
Panels bug her but it's okay to put registers in the beautiful new tile and hardwood floors? Registers that will rust in kitchen, bath areas as well as just get generally nasty. To each their own I guess.

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Stumbled onto a site that makes hydronic baseboard panels that look like baseboard! You never know what is out there without a lot of looking and asking, as long as you are not asking the wrong contractor....
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your first order of business is finding yourself a new hvac contractor, or convince the one you have that he has to do a complete energy load calc for both heating and cooling. Without a load calc, all you are doing is guessing.
Next you need to find a guy who installs hydronic heating for a living and has a clue or two about what he's doing. The hvac guy you got is not going to cut the mustard.
You would be money ahead of the game if you bought Steve Scott a round trip airplane ticket and flew him out to do the load calc and design of your system. Then maybe your hvac guy would have a few clues to go on.
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